Liquid-crystalline polymer films having photo-responsivity are highly functional materials which combine anisotropy based on liquid crystallinity with moldability based on polymer, and researches on their applications have been actively carried out with the hope of practically utilizing such films in various fields.
For example, Non-Patent Document 1 reports the effect of an azobenzene crosslinking agent on molecular length in photo-induced movements of a liquid-crystalline polymer film.
Patent Document 1 discloses a photic driving actuator equipped with an element molded from a cross-linked liquid-crystalline polymer containing photochromic molecules capable of undergoing reversible isomerization when irradiated with ultraviolet light or visible light. Patent Document 2 discloses the photic driving rotor obtained by forming the molded cross-linked liquid-crystalline polymer as cited above into an endless-belt.
Traditional manufacturing of liquid-crystalline polymer films necessitates undergoing complicated processes as mentioned below.
FIG. 2 is a flow process chart illustrating an outline of a traditional method for manufacturing a liquid-crystalline polymer film. The traditional method for manufacturing a liquid-crystalline polymer film has a feedstock preparing process, a cell making process, a photopolymerizing process and a taking-out process. In the feedstock preparing process, a mixture of raw materials containing a liquid-crystalline material, a photopolymerization initiator and so on is blended (S101), and then dried under reduced pressure (S102).
The thus obtained mixture of raw materials is usually in a powdery state, and it is used in the photopolymerizing process described below. In the cell making process performed separately from the feedstock preparing process, a glass substrate as a cell forming material is cleaned (S103), and thereon an alignment film is formed through application of a polyimide coating (S104). The alignment film obtained is subjected to annealing treatment (S105), and then to rubbing treatment (S106).
Two sheets of the thus made alignment film-attached glass substrate are prepared, and they are stuck together to make a cell (S107). In the subsequent photopolymerizing process, the cell obtained in the cell making process is heated first (S108), the powdery mixture of raw materials obtained in the feedstock preparing process is molten and injected into a gap between the two glass substrates of the heated cell with the aid of capillary action (S109), the cell is cooled as a fall in temperature is controlled exactly (S110), and then the feedstock is irradiated with light, thereby undergoing photopolymerization (S111). After the completion of the polymerization, the cell made up of the glass substrates is broken (S112), and the liquid-crystalline polymer film is taken out (S113).    Non-Patent Document 1: Ryuta Sasaki, Jun-ichi Mamiya, Motoi Kinoshita, Atsushi Shishido & Tomiki Ikeda, proceedings of 60th Symposium on Macromolecules (2011), entitled “Photoresponsive Behavior of Crosslinked Liquid-Crystalline Polymer Films with Different Spacer Length of Azobenzene Crosslinker”    Patent Document 1: Japanese Patent No. 5,224,261    Patent Document 2: Japanese Patent No. 5,067,964